A growing body of evidence in the US and UK documents large health disparities by race and socioeconomic status (SES). This project brings together an interdisciplinary team of US and UK investigators with established ties and common objectives to create comparable data in both countries that will permit a better understanding of health disparities and how they might be reduced. We propose to investigate the similarities and differences in social context and discrimination and disadvantage in generating disparities by race/ethnicity and SES in functioning, physical and mental health, and health service use in the US and UK. This project comprises three specific aims: 1) to formalize a collaboration between the US and UK teams; 2) to develop a socio-historical approach to characterizing social context that will enable comparisons of disparities in health and health service use between the US and UK; and illuminate the role of policy in shaping observed patterns within and between countries; and 3) to examine within- and between-country differences in the prevalence of perceived discrimination; and the extent to which discrimination may account for disparities by race/ethnicity and SES in functioning, depression, general physical health, and health service use. This project capitalizes on two extant studies of socioeconomically and racially diverse populations in the US and UK. Using a cross sectional design, we harmonize these studies to construct comparable data on 800 subjects (250 black and 550 white) at each site regarding: a) four key outcomes (functioning, depression, general physical health, and health service use); b) discrimination, coping, stressful circumstances, and related psychosocial variables; c) social context, characterized using a socio-historical approach that will render meaningful cross-country comparisons; and d) individual SES. These data will provide a novel, multi-disciplinary basis for a more detailed understanding the impact of discrimination on health disparities by race/ethnicity and SES in the context of systematic differences and similar social structures in US and UK. In addition, this comparative study has the potential to provide the basis for an ongoing cross-national examination of health disparities as these mid-adult samples age over time. This project focuses on the contribution of discrimination by race/ethnicity, SES, and social context to disparities in health and health service use in the US and the UK. Although these disparities constitute a major public health concern in both countries, there has not yet been a thorough examination of the role discrimination and social context play in driving these disparities both within and between each country.